THE QUESTION Spikes in blood pressure when taken at a doctor’s office are often dismissed as inconsequential, brought on by the stress of the medical appointment. The condition even has a nickname: white coat syndrome. However, might variations in blood pressure indicate something more serious?

THIS STUDY analyzed data on 25,814 adults, most about 66 years old, who were taking various medications to control hypertension (high blood pressure). For 28 months, their blood pressure was measured periodically. Over about the next three years, 1,948 of the participants died for any reason, 1,194 had a non-fatal heart attack or died from coronary heart disease (also called coronary artery disease, or atherosclerosis), 606 had a stroke and 921 developed heart failure.

Those whose blood pressure readings had varied the most — a difference in the systolic (top number) of 14.4 points (mm Hg) or more — were 58 percent more likely to have died for any reason than were those with the least variation. They also were 30 percent more likely to have had a heart attack or to have died from coronary heart disease, 46 percent more likely to have had a stroke and 25 percent more likely to have developed heart failure.

WHO MAY BE AFFECTED? People with hypertension. About a third of U.S. adults have high blood pressure or are taking medication to control it. For most people, a reading of 119/79 or lower is considered normal and 140/90 or higher is considered high blood pressure. Healthy lifestyle habits and, if needed, medication can often keep blood pressure within an acceptable range. Uncontrolled hypertension can contribute to kidney failure and numerous heart and cardiovascular problems.

CAVEATS The study did not test whether reducing variations in blood pressure would reduce the risk for heart problems. The study found an association between variations in blood pressure and several heart conditions, but it did not establish direct cause and effect. Blood pressure medicines taken by the study participants were provided by the AstraZeneca, Bristol-Myers Squibb and Pfizer pharmaceutical companies; Pfizer also helped fund the study.

FIND THIS STUDY July 28 online issue of Annals of Internal Medicine (www.annals.org; click “Online First”)

LEARN MORE ABOUT hypertension at nhlbi.nih.gov/health (click on “A to Z Index,” then “H” and “High Blood Pressure”) and www.familydoctor.org.

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.